Tuesday 27 May 2014 04.28 EDT
First published on Tuesday 27 May 2014 04.28 EDT

Satellite data used to narrow down the search for the missing Malaysia Airlines plane, MH370, has been released after demands from relatives of the passengers.

The data [pdf], which was drawn up by the British company Inmarsat, was released 80 days after the Boeing vanished with 239 people on board.

It consists of a 47-page table of satellite logs from 4pm on 7 March when the plane took off from Kuala Lumpur until its last known contact of this type early the next day. Malaysia's civil aviation authority said the raw data was being released for "public consumption".

The data was used by Inmarsat to calculate that the Beijing-bound plane changed course and was likely to have gone down in the southern Indian Ocean. No trace of the plane has yet been found despite an extensive search in the area led by Australia, first on the surface by air and boat, and then underwater using specialist submarines.

Explanatory notes to the newly released data point out that the ping signals were used to estimate the distance between the satellite and the aircraft, but that they do not pinpoint its exact location.

Family members of the missing passengers have called for the data to be made public for independent analysis. They have criticised the Malaysian authorities for the way information about the search has been released and claimed they were wrong to give up hope by concluding that the plane went missing in the southern Indian Ocean.

Last week in a report to the governments of Malaysia and Australia they said: "There is no mention on why they are so sure the Inmarsat data is highly accurate and reliable."

Inmarsat's interpretation of the data has been verified by the international investigation team, which includes Malaysia's Department for Civil Aviation, the US National Transport Safety Board, Britain's Air Accidents Investigations Branch, and China's Aircraft Accident Investigation Department.

Analysts said it would take time to draw any conclusions from the new technical data.

Shukor Yusof, an aviation analyst with Malaysia-based Endau Analytics, said the satellite data was "highly technical" and required an expert to decode.

"There are very few people who can make head or tail as to what the numbers indicate. To me as a layman, it looks like a sequence of signals that were given out by the aircraft possibly indicating its flight path," he said.

Greg Waldron, Singapore-based managing editor with aviation publication group Flightglobal, said the satellite data was consistent with what Inmarsat had previously revealed.

"Basically it shows the timings of the handshakes of the plane with the satellite over the Indian Ocean," he said.

"But I would not dare to guess if they are searching in the right place. The fact that they are using this type of data shows how desperate the search for the plane is."

Malaysia's civil aviation authority previously stressed that satellite data was just one of several elements being examined by investigators.

Australia has committed up to £50m towards the search operation over two years.